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Heart Of James Webb Space Telescope Survives Deep Freeze

A crane lifts the heart of the James Webb Space Telescope from the Goddard Thermal Vacuum Chamber where it spent weeks in a space-like environment. Image Credit: NASA/Chris Gunn

October 21, 2014 – After 116 days of being subjected to extremely frigid temperatures like those it will encounter in space, the heart of the James Webb Space Telescope (JWST) emerged unscathed from the thermal vacuum chamber at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Teams of engineers and technicians have been monitoring the complex Integrated Science Instrument Module (ISIM) and its sensitive instruments around the clock since it was lowered into the chamber for its summer-long test.

Engineer Mike Drury, the ISIM Lead Integration and Test Engineer, is one of the test directors making sure that Webb will thrive in the frigid conditions at its final destination in space one million miles away from Earth.

“The telescope is going to L2 or Lagrange Point 2, which is a very extreme environment,” said Drury. “The heart of Webb, called ISIM, is a very important part of the observatory and will provide all of Webb’s images.”

ISIM weighs about as much as an elephant. Inside its black composite frame the four science instruments are tightly packed and are specially designed to capture specific information about distant light in the universe.The images it captures will reveal the first galaxies forming 13.5 billion years ago. The telescope will also pierce through interstellar dust clouds to capture stars and planets forming in our own galaxy.

JWST will be operating in temperatures far colder than any place on the Earth’s surface. The telescope could be subjected to temperatures as low as -387 degrees Fahrenheit, or 40 degrees Kelvin. To create temperatures that cold on Earth, the team uses the massive thermal vacuum chamber at Goddard called the Space Environment Simulator, or SES, that duplicates the vacuum and extreme temperatures of space. This 40-foot-tall, 27-foot-diameter cylindrical chamber eliminates the tiniest trace of air with vacuum pumps and uses liquid nitrogen and even colder liquid helium to create temperatures that simulate the space environment.

“We complete these tests to make sure that when this telescope cools down, the four parts of the heart are still positioned meticulously so that when light enters the telescope we capture it the right way,” said Paul Geithner, Webb’s deputy project manger. “The biggest stress for this telescope will be when it cools down. When the telescope structure goes from room temperature to its super cold operating temperature, it will see more stress from shrinkage than it will from violent vibration during launch,” said Geithner.

At any given time of day during the test, the control room held representatives from all four instrument teams. Each instrument has a test engineer, who makes sure the test is going well, and a data analyzer. Those teams are testing the hundreds of electrical connections and computer programs that give life to Webb’s heart.

Once the test was completed, the team warmed up the chamber, and completed the final functional test and a series of data analyses before they opened up the chamber.

“We’ve been very fortunate on this test. We’ve worked with all of the different teams. We have all been working shifts and pitching in,” said Drury. “I’m really amazed at how well everyone is getting along together. We have a lot of people who are willing to help out.”

The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, the European Space Agency and the Canadian Space Agency.

Colorado’s Ball Aerospace & Technologies Corp. is responsible for the eighteen primary mirrors that make up the James Webb Space Telescope. Once on orbit, the 18 hexagonal segments will work together as one 21.3-foot (6.5-meter) primary mirror, the largest mirror ever flown in space and the first to deploy in space. Ball Aerospace was also responsible for developing the secondary mirror, tertiary mirror and fine-steering mirror.